Dynamic reconfiguration of electrodes in an active stylus

ABSTRACT

In one embodiment, a method includes identifying a change in an operating characteristic of a stylus. The stylus is operable to communicate wirelessly with a device through a touch sensor of the device, and the stylus includes one or more electrodes. The method includes, in response to the change, dynamically configuring an electrode for the operating characteristic of the stylus as changed.

RELATED APPLICATION

This application claims the benefit, under 35 U.S.C. §119(e), of U.S.Provisional Patent Application No. 61/553114, filed 28 Oct. 2011, whichis incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to touch-position sensors.

BACKGROUND

A touch sensor may detect the presence and location of a touch or theproximity of an object (such as a user's finger or a stylus) within atouch-sensitive area of the touch sensor overlaid on a display screen,for example. In a touch-sensitive-display application, the touch sensormay enable a user to interact directly with what is displayed on thescreen, rather than indirectly with a mouse or touch pad. A touch sensormay be attached to or provided as part of a desktop computer, laptopcomputer, tablet computer, personal digital assistant (PDA), smartphone,satellite navigation device, portable media player, portable gameconsole, kiosk computer, point-of-sale device, or other suitable device.A control panel on a household or other appliance may include a touchsensor.

There are a number of different types of touch sensors, such as, forexample, resistive touch screens, surface acoustic wave touch screens,and capacitive touch screens. Herein, reference to a touch sensor mayencompass a touch screen, and vice versa, where appropriate. When anobject touches or comes within proximity of the surface of thecapacitive touch screen, a change in capacitance may occur within thetouch screen at the location of the touch or proximity. A touch-sensorcontroller may process the change in capacitance to determine itsposition on the touch screen.

SUMMARY

In particular embodiments, a stylus may include one or more electrodes.The stylus may be operable to communicate wirelessly with a devicethrough a touch sensor of the device. A change in an operatingcharacteristic of the stylus may be identified. In response to thechange in the operating characteristic of the stylus, an electrode ofthe stylus may be dynamically configured. The electrode of the stylusmay be dynamically configured based on the change in the operatingcharacteristic. The embodiments disclosed above are only examples, andthe scope of this disclosure is not limited to them. Particularembodiments may include all, some, or none of the components, elements,features, functions, operations, or steps of the embodiments disclosedabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example touch sensor with an example touch-sensorcontroller.

FIG. 2 illustrates an example active stylus exterior.

FIG. 3 illustrates an example active stylus interior.

FIG. 4 illustrates an example active stylus with touch sensor device.

FIG. 5A illustrates an example multi-electrode active stylus tip.

FIG. 5B illustrates a head-on view of an example multi-electrodeactive-stylus tip.

FIG. 6A illustrates an example multi-electrode active stylus tip.

FIG. 6B illustrates a head-on view of an example multi-electrodeactive-stylus tip.

FIG. 6C illustrates an example multi-electrode active stylus tip.

FIG. 6D illustrates a head-on view of an example multi-electrodeactive-stylus tip.

FIG. 7A illustrates an example multi-electrode active stylus tip.

FIG. 7B illustrates a head-on view of an example multi-electrodeactive-stylus tip.

FIG. 7C illustrates an example multi-electrode active stylus tip.

FIG. 7D illustrates a head-on view of an example multi-electrodeactive-stylus tip.

FIG. 8A illustrates an example multi-electrode active stylus tip.

FIG. 8B illustrates an example multi-electrode active stylus tip.

FIG. 9 illustrates an example system for adjusting a received signalthreshold in an active stylus.

FIG. 10 illustrates an example method for adjusting a received signalthreshold in an active stylus.

FIG. 11 illustrates an example method for dynamically reconfiguringelectrodes in an active stylus.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 illustrates an example touch sensor 10 with an exampletouch-sensor controller 12. Touch sensor 10 and touch-sensor controller12 may detect the presence and location of a touch or the proximity ofan object within a touch-sensitive area of touch sensor 10. Herein,reference to a touch sensor may encompass both the touch sensor and itstouch-sensor controller, where appropriate. Similarly, reference to atouch-sensor controller may encompass both the touch-sensor controllerand its touch sensor, where appropriate. Touch sensor 10 may include oneor more touch-sensitive areas, where appropriate. Touch sensor 10 mayinclude an array of drive and sense electrodes (or an array ofelectrodes of a single type) disposed on one or more substrates, whichmay be made of a dielectric material. Herein, reference to a touchsensor may encompass both the electrodes of the touch sensor and thesubstrate(s) that they are disposed on, where appropriate.Alternatively, where appropriate, reference to a touch sensor mayencompass the electrodes of the touch sensor, but not the substrate(s)that they are disposed on.

An electrode (whether a ground electrode, guard electrode, driveelectrode, or sense electrode) may be an area of conductive materialforming a shape, such as for example a disc, square, rectangle, thinline, other suitable shape, or suitable combination of these. One ormore cuts in one or more layers of conductive material may (at least inpart) create the shape of an electrode, and the area of the shape may(at least in part) be bounded by those cuts. In particular embodiments,the conductive material of an electrode may occupy approximately 100% ofthe area of its shape. As an example and not by way of limitation, anelectrode may be made of indium tin oxide (ITO) and the ITO of theelectrode may occupy approximately 100% of the area of its shape(sometimes referred to as a 100% fill), where appropriate. In particularembodiments, the conductive material of an electrode may occupysubstantially less than 100% of the area of its shape. As an example andnot by way of limitation, an electrode may be made of fine lines ofmetal or other conductive material (FLM), such as for example copper,silver, or a copper- or silver-based material, and the fine lines ofconductive material may occupy approximately 5% of the area of its shapein a hatched, mesh, or other suitable pattern. Herein, reference to FLMencompasses such material, where appropriate. Although this disclosuredescribes or illustrates particular electrodes made of particularconductive material forming particular shapes with particular fillpercentages having particular patterns, this disclosure contemplates anysuitable electrodes made of any suitable conductive material forming anysuitable shapes with any suitable fill percentages having any suitablepatterns.

Where appropriate, the shapes of the electrodes (or other elements) of atouch sensor may constitute in whole or in part one or moremacro-features of the touch sensor. One or more characteristics of theimplementation of those shapes (such as, for example, the conductivematerials, fills, or patterns within the shapes) may constitute in wholeor in part one or more micro-features of the touch sensor. One or moremacro-features of a touch sensor may determine one or morecharacteristics of its functionality, and one or more micro-features ofthe touch sensor may determine one or more optical features of the touchsensor, such as transmittance, refraction, or reflection.

A mechanical stack may contain the substrate (or multiple substrates)and the conductive material forming the drive or sense electrodes oftouch sensor 10. As an example and not by way of limitation, themechanical stack may include a first layer of optically clear adhesive(OCA) beneath a cover panel. The cover panel may be clear and made of aresilient material suitable for repeated touching, such as for exampleglass, polycarbonate, or poly(methyl methacrylate) (PMMA). Thisdisclosure contemplates any suitable cover panel made of any suitablematerial. The first layer of OCA may be disposed between the cover paneland the substrate with the conductive material forming the drive orsense electrodes. The mechanical stack may also include a second layerof OCA and a dielectric layer (which may be made of PET or anothersuitable material, similar to the substrate with the conductive materialforming the drive or sense electrodes). As an alternative, whereappropriate, a thin coating of a dielectric material may be appliedinstead of the second layer of OCA and the dielectric layer. The secondlayer of OCA may be disposed between the substrate with the conductivematerial making up the drive or sense electrodes and the dielectriclayer, and the dielectric layer may be disposed between the second layerof OCA and an air gap to a display of a device including touch sensor 10and touch-sensor controller 12. As an example only and not by way oflimitation, the cover panel may have a thickness of approximately 1 mm;the first layer of OCA may have a thickness of approximately 0.05 mm;the substrate with the conductive material forming the drive or senseelectrodes may have a thickness of approximately 0.05 mm; the secondlayer of OCA may have a thickness of approximately 0.05 mm; and thedielectric layer may have a thickness of approximately 0.05 mm. Althoughthis disclosure describes a particular mechanical stack with aparticular number of particular layers made of particular materials andhaving particular thicknesses, this disclosure contemplates any suitablemechanical stack with any suitable number of any suitable layers made ofany suitable materials and having any suitable thicknesses. As anexample and not by way of limitation, in particular embodiments, a layerof adhesive or dielectric may replace the dielectric layer, second layerof OCA, and air gap described above, with there being no air gap to thedisplay.

One or more portions of the substrate of touch sensor 10 may be made ofpolyethylene terephthalate (PET) or another suitable material. Thisdisclosure contemplates any suitable substrate with any suitableportions made of any suitable material. In particular embodiments, thedrive or sense electrodes in touch sensor 10 may be made of ITO in wholeor in part. In particular embodiments, the drive or sense electrodes intouch sensor 10 may be made of fine lines of metal or other conductivematerial. As an example and not by way of limitation, one or moreportions of the conductive material may be copper or copper-based andhave a thickness of approximately 5 μm or less and a width ofapproximately 10 μm or less. As another example, one or more portions ofthe conductive material may be silver or silver-based and similarly havea thickness of approximately 5 μm or less and a width of approximately10 μm or less. This disclosure contemplates any suitable electrodes madeof any suitable material.

Touch sensor 10 may implement a capacitive form of touch sensing. In amutual-capacitance implementation, touch sensor 10 may include an arrayof drive and sense electrodes forming an array of capacitive nodes. Adrive electrode and a sense electrode may form a capacitive node. Thedrive and sense electrodes forming the capacitive node may come neareach other, but not make electrical contact with each other. Instead,the drive and sense electrodes may be capacitively coupled to each otheracross a space between them. A pulsed or alternating voltage applied tothe drive electrode (by touch-sensor controller 12) may induce a chargeon the sense electrode, and the amount of charge induced may besusceptible to external influence (such as a touch or the proximity ofan object). When an object touches or comes within proximity of thecapacitive node, a change in capacitance may occur at the capacitivenode and touch-sensor controller 12 may measure the change incapacitance. By measuring changes in capacitance throughout the array,touch-sensor controller 12 may determine the position of the touch orproximity within the touch-sensitive area(s) of touch sensor 10.

In a self-capacitance implementation, touch sensor 10 may include anarray of electrodes of a single type that may each form a capacitivenode. When an object touches or comes within proximity of the capacitivenode, a change in self-capacitance may occur at the capacitive node andcontroller 12 may measure the change in capacitance, for example, as achange in the amount of charge needed to raise the voltage at thecapacitive node by a pre-determined amount. As with a mutual-capacitanceimplementation, by measuring changes in capacitance throughout thearray, controller 12 may determine the position of the touch orproximity within the touch-sensitive area(s) of touch sensor 10. Thisdisclosure contemplates any suitable form of capacitive touch sensing,where appropriate.

In particular embodiments, one or more drive electrodes may togetherform a drive line running horizontally or vertically or in any suitableorientation. Similarly, one or more sense electrodes may together form asense line running horizontally or vertically or in any suitableorientation. In particular embodiments, drive lines may runsubstantially perpendicular to sense lines. Herein, reference to a driveline may encompass one or more drive electrodes making up the driveline, and vice versa, where appropriate. Similarly, reference to a senseline may encompass one or more sense electrodes making up the senseline, and vice versa, where appropriate.

Touch sensor 10 may have drive and sense electrodes disposed in apattern on one side of a single substrate. In such a configuration, apair of drive and sense electrodes capacitively coupled to each otheracross a space between them may form a capacitive node. For aself-capacitance implementation, electrodes of only a single type may bedisposed in a pattern on a single substrate. In addition or as analternative to having drive and sense electrodes disposed in a patternon one side of a single substrate, touch sensor 10 may have driveelectrodes disposed in a pattern on one side of a substrate and senseelectrodes disposed in a pattern on another side of the substrate.Moreover, touch sensor 10 may have drive electrodes disposed in apattern on one side of one substrate and sense electrodes disposed in apattern on one side of another substrate. In such configurations, anintersection of a drive electrode and a sense electrode may form acapacitive node. Such an intersection may be a location where the driveelectrode and the sense electrode “cross” or come nearest each other intheir respective planes. The drive and sense electrodes do not makeelectrical contact with each other—instead they are capacitively coupledto each other across a dielectric at the intersection. Although thisdisclosure describes particular configurations of particular electrodesforming particular nodes, this disclosure contemplates any suitableconfiguration of any suitable electrodes forming any suitable nodes.Moreover, this disclosure contemplates any suitable electrodes disposedon any suitable number of any suitable substrates in any suitablepatterns.

As described above, a change in capacitance at a capacitive node oftouch sensor 10 may indicate a touch or proximity input at the positionof the capacitive node. Touch-sensor controller 12 may detect andprocess the change in capacitance to determine the presence and locationof the touch or proximity input. Touch-sensor controller 12 may thencommunicate information about the touch or proximity input to one ormore other components (such one or more central processing units (CPUs))of a device that includes touch sensor 10 and touch-sensor controller12, which may respond to the touch or proximity input by initiating afunction of the device (or an application running on the device).Although this disclosure describes a particular touch-sensor controllerhaving particular functionality with respect to a particular device anda particular touch sensor, this disclosure contemplates any suitabletouch-sensor controller having any suitable functionality with respectto any suitable device and any suitable touch sensor.

Touch-sensor controller 12 may be one or more integrated circuits (ICs),such as for example general-purpose microprocessors, microcontrollers,programmable logic devices (PLDs) or programmable logic arrays (PLAs),application-specific ICs (ASICs). In particular embodiments,touch-sensor controller 12 comprises analog circuitry, digital logic,and digital non-volatile memory. In particular embodiments, touch-sensorcontroller 12 is disposed on a flexible printed circuit (FPC) bonded tothe substrate of touch sensor 10, as described below. The FPC may beactive or passive, where appropriate. In particular embodiments multipletouch-sensor controllers 12 are disposed on the FPC. Touch-sensorcontroller 12 may include a processor unit, a drive unit, a sense unit,and a storage unit. The drive unit may supply drive signals to the driveelectrodes of touch sensor 10. The sense unit may sense charge at thecapacitive nodes of touch sensor 10 and provide measurement signals tothe processor unit representing capacitances at the capacitive nodes.The processor unit may control the supply of drive signals to the driveelectrodes by the drive unit and process measurement signals from thesense unit to detect and process the presence and location of a touch orproximity input within the touch-sensitive area(s) of touch sensor 10.The processor unit may also track changes in the position of a touch orproximity input within the touch-sensitive area(s) of touch sensor 10.The storage unit may store programming for execution by the processorunit, including programming for controlling the drive unit to supplydrive signals to the drive electrodes, programming for processingmeasurement signals from the sense unit, and other suitable programming,where appropriate. Although this disclosure describes a particulartouch-sensor controller having a particular implementation withparticular components, this disclosure contemplates any suitabletouch-sensor controller having any suitable implementation with anysuitable components.

Tracks 14 of conductive material disposed on the substrate of touchsensor 10 may couple the drive or sense electrodes of touch sensor 10 toconnection pads 16, also disposed on the substrate of touch sensor 10.As described below, connection pads 16 facilitate coupling of tracks 14to touch-sensor controller 12. Tracks 14 may extend into or around (e.g.at the edges of) the touch-sensitive area(s) of touch sensor 10.Particular tracks 14 may provide drive connections for couplingtouch-sensor controller 12 to drive electrodes of touch sensor 10,through which the drive unit of touch-sensor controller 12 may supplydrive signals to the drive electrodes. Other tracks 14 may provide senseconnections for coupling touch-sensor controller 12 to sense electrodesof touch sensor 10, through which the sense unit of touch-sensorcontroller 12 may sense charge at the capacitive nodes of touch sensor10. Tracks 14 may be made of fine lines of metal or other conductivematerial. As an example and not by way of limitation, the conductivematerial of tracks 14 may be copper or copper-based and have a width ofapproximately 100 μm or less. As another example, the conductivematerial of tracks 14 may be silver or silver-based and have a width ofapproximately 100 μm or less. In particular embodiments, tracks 14 maybe made of ITO in whole or in part in addition or as an alternative tofine lines of metal or other conductive material. Although thisdisclosure describes particular tracks made of particular materials withparticular widths, this disclosure contemplates any suitable tracks madeof any suitable materials with any suitable widths. In addition totracks 14, touch sensor 10 may include one or more ground linesterminating at a ground connector (which may be a connection pad 16) atan edge of the substrate of touch sensor 10 (similar to tracks 14).

Connection pads 16 may be located along one or more edges of thesubstrate, outside the touch-sensitive area(s) of touch sensor 10. Asdescribed above, touch-sensor controller 12 may be on an FPC. Connectionpads 16 may be made of the same material as tracks 14 and may be bondedto the FPC using an anisotropic conductive film (ACF). Connection 18 mayinclude conductive lines on the FPC coupling touch-sensor controller 12to connection pads 16, in turn coupling touch-sensor controller 12 totracks 14 and to the drive or sense electrodes of touch sensor 10. Inanother embodiment, connection pads 16 may be connected to anelectro-mechanical connector (such as a zero insertion forcewire-to-board connector); in this embodiment, connection 18 may not needto include an FPC. This disclosure contemplates any suitable connection18 between touch-sensor controller 12 and touch sensor 10.

FIG. 2 illustrates an example exterior of an example active stylus 20.Active stylus 20 may include one or more components, such as buttons 30or sliders 32 and 34 integrated with an outer body 22. These externalcomponents may provide for interaction between active stylus 20 and auser or between a device and a user. As an example and not by way oflimitation, interactions may include communication between active stylus20 and a device, enabling or altering functionality of active stylus 20or a device, or providing feedback to or accepting input from one ormore users. The device may by any suitable device, such as, for exampleand without limitation, a desktop computer, laptop computer, tabletcomputer, personal digital assistant (PDA), smartphone, satellitenavigation device, portable media player, portable game console, kioskcomputer, point-of-sale device, or other suitable device. Although thisdisclosure provides specific examples of particular componentsconfigured to provide particular interactions, this disclosurecontemplates any suitable component configured to provide any suitableinteraction. Active stylus 20 may have any suitable dimensions withouter body 22 made of any suitable material or combination of materials,such as, for example and without limitation, plastic or metal. Inparticular embodiments, exterior components (e.g. 30 or 32) of activestylus 20 may interact with internal components or programming of activestylus 20 or may initiate one or more interactions with one or moredevices or other active styluses 20.

As described above, actuating one or more particular components mayinitiate an interaction between active stylus 20 and a user or betweenthe device and the user. Components of active stylus 20 may include oneor more buttons 30 or one or more sliders 32 and 34. As an example andnot by way of limitation, buttons 30 or sliders 32 and 34 may bemechanical or capacitive and may function as a roller, trackball, orwheel. As another example, one or more sliders 32 or 34 may function asa vertical slider 34 aligned along a longitudinal axis, while one ormore wheel sliders 32 may be aligned along the circumference of activestylus 20. In particular embodiments, capacitive sliders 32 and 34 orbuttons 30 may be implemented using one or more touch-sensitive areas.Touch-sensitive areas may have any suitable shape, dimensions, location,or be made from any suitable material. As an example and not by way oflimitation, sliders 32 and 34 or buttons 30 may be implemented usingareas of flexible mesh formed using lines of conductive material. Asanother example, sliders 32 and 34 or buttons 30 may be implementedusing a FPC.

Active stylus 20 may have one or more components configured to providefeedback to or accepting feedback from a user, such as, for example andwithout limitation, tactile, visual, or audio feedback. Active stylus 20may include one or more ridges or grooves 24 on its outer body 22.Ridges or grooves 24 may have any suitable dimensions, have any suitablespacing between ridges or grooves, or be located at any suitable area onouter body 22 of active stylus 20. As an example and not by way oflimitation, ridges 24 may enhance a user's grip on outer body 22 ofactive stylus 20 or provide tactile feedback to or accept tactile inputfrom a user. Active stylus 20 may include one or more audio components38 capable of transmitting and receiving audio signals. As an exampleand not by way of limitation, audio component 38 may contain amicrophone capable of recording or transmitting one or more users'voices. As another example, audio component 38 may provide an auditoryindication of a power status of active stylus 20. Active stylus 20 mayinclude one or more visual feedback components 36, such as alight-emitting diode (LED) indicator. As an example and not by way oflimitation, visual feedback component 36 may indicate a power status ofactive stylus 20 to the user.

One or more modified surface areas 40 may form one or more components onouter body 22 of active stylus 20. Properties of modified surface areas40 may be different than properties of the remaining surface of outerbody 22. As an example and not by way of limitation, modified surfacearea 40 may be modified to have a different texture, temperature, orelectromagnetic characteristic relative to the surface properties of theremainder of outer body 22. Modified surface area 40 may be capable ofdynamically altering its properties, for example by using hapticinterfaces or rendering techniques. A user may interact with modifiedsurface area 40 to provide any suitable functionally. For example andnot by way of limitation, dragging a finger across modified surface area40 may initiate an interaction, such as data transfer, between activestylus 20 and a device.

One or more components of active stylus 20 may be configured tocommunicate data between active stylus 20 and the device. For example,active stylus 20 may include one or more tips 26 or nibs. Tip 26 mayinclude one or more electrodes configured to communicate data betweenactive stylus 20 and one or more devices or other active styluses. Tip26 may be made of any suitable material, such as a conductive material,and have any suitable dimensions, such as, for example, a diameter of 1mm or less at its terminal end. Active stylus 20 may include one or moreports 28 located at any suitable location on outer body 22 of activestylus 20. Port 28 may be configured to transfer signals or informationbetween active stylus 20 and one or more devices or power sources. Port28 may transfer signals or information by any suitable technology, suchas, for example, by universal serial bus (USB) or Ethernet connections.Although this disclosure describes and illustrates a particularconfiguration of particular components with particular locations,dimensions, composition and functionality, this disclosure contemplatesany suitable configuration of suitable components with any suitablelocations, dimensions, composition, and functionality with respect toactive stylus 20.

FIG. 3 illustrates an example internal components of example activestylus 20. Active stylus 20 may include one or more internal components,such as a controller 50, sensors 42, memory 44, or power source 48. Inparticular embodiments, one or more internal components may beconfigured to provide for interaction between active stylus 20 and auser or between a device and a user. In other particular embodiments,one or more internal components, in conjunction with one or moreexternal components described above, may be configured to provideinteraction between active stylus 20 and a user or between a device anda user. As an example and not by way of limitation, interactions mayinclude communication between active stylus 20 and a device, enabling oraltering functionality of active stylus 20 or a device, or providingfeedback to or accepting input from one or more users.

Controller 50 may be a microcontroller or any other type of processorsuitable for controlling the operation of active stylus 20. Controller50 may be one or more ICs—such as, for example, general-purposemicroprocessors, microcontrollers, PLDs, PLAs, or ASICs. Controller 50may include a processor unit, a drive unit, a sense unit, and a storageunit. The drive unit may supply signals to electrodes of tip 26 throughcenter shaft 41. The drive unit may also supply signals to control ordrive sensors 42 or one or more external components of active stylus 20.The sense unit may sense signals received by electrodes of tip 26through center shaft 41 and provide measurement signals to the processorunit representing input from a device. The sense unit may also sensesignals generated by sensors 42 or one or more external components andprovide measurement signals to the processor unit representing inputfrom a user. The processor unit may control the supply of signals to theelectrodes of tip 26 and process measurement signals from the sense unitto detect and process input from the device. The processor unit may alsoprocess measurement signals from sensors 42 or one or more externalcomponents. The storage unit may store programming for execution by theprocessor unit, including programming for controlling the drive unit tosupply signals to the electrodes of tip 26, programming for processingmeasurement signals from the sense unit corresponding to input from thedevice, programming for processing measurement signals from sensors 42or external components to initiate a pre-determined function or gestureto be performed by active stylus 20 or the device, and other suitableprogramming, where appropriate. As an example and not by way oflimitation, programming executed by controller 50 may electronicallyfilter signals received from the sense unit. Although this disclosuredescribes a particular controller 50 having a particular implementationwith particular components, this disclosure contemplates any suitablecontroller having any suitable implementation with any suitablecomponents.

In particular embodiments, active stylus 20 may include one or moresensors 42, such as touch sensors, gyroscopes, accelerometers, contactsensors, or any other type of sensor that detect or measure data aboutthe environment in which active stylus 20 operates. Sensors 42 maydetect and measure one or more characteristic of active stylus 20, suchas acceleration or movement, orientation, contact, pressure on outerbody 22, force on tip 26, vibration, or any other suitablecharacteristic of active stylus 20. As an example and not by way oflimitation, sensors 42 may be implemented mechanically, electronically,or capacitively. As described above, data detected or measured bysensors 42 communicated to controller 50 may initiate a pre-determinedfunction or gesture to be performed by active stylus 20 or the device.In particular embodiments, data detected or received by sensors 42 maybe stored in memory 44. Memory 44 may be any form of memory suitable forstoring data in active stylus 20. In other particular embodiments,controller 50 may access data stored in memory 44. As an example and notby way of limitation, memory 44 may store programming for execution bythe processor unit of controller 50. As another example, data measuredby sensors 42 may be processed by controller 50 and stored in memory 44.

Power source 48 may be any type of stored-energy source, includingelectrical or chemical-energy sources, suitable for powering theoperation of active stylus 20. In particular embodiments, power source48 may be charged by energy from a user or device. As an example and notby way of limitation, power source 48 may be a rechargeable battery thatmay be charged by motion induced on active stylus 20. In otherparticular embodiments, power source 48 of active stylus 20 may providepower to or receive power from the device. As an example and not by wayof limitation, power may be inductively transferred between power source48 and a power source of the device.

FIG. 4 illustrates an example active stylus 20 with an example device52. Device 52 may have a display (not shown) and a touch sensor with atouch-sensitive area 54. Device 52 display may be a liquid crystaldisplay (LCD), a LED display, a LED-backlight LCD, or other suitabledisplay and may be visible though a cover panel and substrate (and thedrive and sense electrodes of the touch sensor disposed on it) of device52. Although this disclosure describes a particular device display andparticular display types, this disclosure contemplates any suitabledevice display and any suitable display types.

Device 52 electronics may provide the functionality of device 52. Asexample and not by way of limitation, device 52 electronics may includecircuitry or other electronics for wireless communication to or fromdevice 52, execute programming on device 52, generating graphical orother user interfaces (UIs) for device 52 display to display to a user,managing power to device 52 from a battery or other power source, takingstill pictures, recording video, other suitable functionality, or anysuitable combination of these. Although this disclosure describesparticular device electronics providing particular functionality of aparticular device, this disclosure contemplates any suitable deviceelectronics providing any suitable functionality of any suitable device.

In particular embodiments, active stylus 20 and device 52 may besynchronized prior to communication of data between active stylus 20 anddevice 52. As an example and not by way of limitation, active stylus 20may be synchronized to device through a pre-determined bit sequencetransmitted by the touch sensor of device 52. As another example, activestylus 20 may be synchronized to device by processing the drive signaltransmitted by drive electrodes of the touch sensor of device 52. Activestylus 20 may interact or communicate with device 52 when active stylus20 is brought in contact with or in proximity to touch-sensitive area 54of the touch sensor of device 52. In particular embodiments, interactionbetween active stylus 20 and device 52 may be capacitive or inductive.As an example and not by way of limitation, when active stylus 20 isbrought in contact with or in the proximity of touch-sensitive area 54of device 52, signals generated by active stylus 20 may influencecapacitive nodes of touch-sensitive area of device 52 or vice versa. Asanother example, a power source of active stylus 20 may be inductivelycharged through the touch sensor of device 52, or vice versa. Althoughthis disclosure describes particular interactions and communicationsbetween active stylus 20 and device 52, this disclosure contemplates anysuitable interactions and communications through any suitable means,such as mechanical forces, current, voltage, or electromagnetic fields.

In particular embodiments, measurement signal from the sensors of activestylus 20 may initiate, provide for, or terminate interactions betweenactive stylus 20 and one or more devices 52 or one or more users, asdescribed above. Interaction between active stylus 20 and device 52 mayoccur when active stylus 20 is contacting or in proximity to device 52.As an example and not by way of limitation, a user may perform a gestureor sequence of gestures, such as shaking or inverting active stylus 20,whilst active stylus 20 is hovering above touch-sensitive area 54 ofdevice 52. Active stylus may interact with device 52 based on thegesture performed with active stylus 20 to initiate a pre-determinedfunction, such as authenticating a user associated with active stylus 20or device 52. Although this disclosure describes particular movementsproviding particular types of interactions between active stylus 20 anddevice 52, this disclosure contemplates any suitable movementinfluencing any suitable interaction in any suitable way.

FIG. 5A illustrates an example active stylus tip 26. Active stylus tip26 may include one or more electrodes 60, 62, and 64 configured tocommunicate data between active stylus 20 and one or more devices orother active styluses. Active stylus tip 26 may include furthercomponents or functionality not illustrated in FIG. 5, 6, 7, or 8. As anexample, active stylus tip 26 may include one or more mechanicalswitches operable to physically switch the connectivity of one or moreelectrodes in the tip. As another example, active stylus tip 26 mayinclude logic, including, for example, a multiplexer. As yet anotherexample, active stylus tip may include electric or electronic circuitelements, including, for example, an operational amplifier.

As an example and without limitation, an electrode in active stylus tip26 may be a ground electrode, a guard electrode, a drive electrode, or asense electrode. The electrodes in active stylus tip 26 may each be anarea of conductive material forming a shape, such as for example a disc,square, rectangle, other suitable shapes, or suitable combination ofthese. One or more cuts in one or more layers of conductive material may(at least in part) create the shape of an electrode, and the area of theshape may (at least in part) be bounded by those cuts. In particularembodiments, the conductive material of an electrode may occupyapproximately 100% of the area of its shape. As an example and not byway of limitation, an electrode may be made of indium tin oxide (ITO)and the ITO of the electrode may occupy approximately 100% of the areaof its shape, where appropriate. In particular embodiments, theconductive material of an electrode may occupy substantially less than100% of the area of its shape. As an example and not by way oflimitation, an electrode may be made of fine lines of metal or otherconductive material (such as for example copper, silver, or a copper- orsilver-based material) and the fine lines of conductive material mayoccupy substantially less than 100% of the area of its shape in ahatched, mesh, or other suitable patterns. The electrodes in activestylus tip 26 may, in particular embodiments, be disposed on a surfaceof active stylus tip 26, or in a region in active stylus tip 26. Inparticular embodiments, the electrodes may be disposed on one or moresubstrates in active stylus tip 26. As an example, active stylus tip 26may contain multiple substrates, and each substrate may have oneelectrode disposed on it. As another example, active stylus tip 26 maycontain multiple substrates, and each substrate may have multipleelectrodes disposed on it. The substrates may be arranged in anysuitable fashion in active stylus tip 26, including having thesubstrates each be a layer (resting on other substrates or layers) onthe surface of active stylus 26. As another example, an electrode may bedisposed in (e.g., embedded within) a substrate. Although thisdisclosure describes or illustrates particular electrodes made ofparticular conductive material forming particular shapes with particularfills having particular patterns, this disclosure contemplates anysuitable electrodes made of any suitable conductive material forming anysuitable shapes with any suitable fills having any suitable patterns.Where appropriate, the shapes of the electrodes (or other elements) ofthe active stylus tip 26 may constitute in whole or in part one or moremacro-features of the active stylus tip 26. One or more characteristicsof the implementation of those shapes (such as, for example, theconductive materials, fills, or patterns within the shapes) mayconstitute in whole or in part one or more micro-features of the activestylus tip 26. One or more macro-features of an active stylus tip 26 maydetermine one or more characteristics of its functionality, and one ormore micro-features of the active stylus tip 26 may determine one ormore optical features of the active stylus tip 26, such astransmittance, refraction, or reflection.

In the example embodiment illustrated in FIG. 5A, active stylus tip 26contains one or more electrodes, including electrodes 60, 62, and 64.The electrodes are disposed on a surface of active stylus tip 26 and arestacked upon one another on the surface, such that the area comprisingelectrode 62 sits adjacent to and above electrode 60, and the areacomprising electrode 64 sits adjacent to and above electrode 62 on theactive stylus tip 26. The electrodes in this embodiment each comprise ahorizontal segment of the surface active stylus tip 26. FIG. 5Billustrates an alternate view of the example embodiment of active stylustip 26 illustrated in FIG. 5A. In FIG. 5B, active stylus tip 26 isviewed head-on, such that each horizontal segment of the tip in FIG. 5Acorresponds to a circular or ring-like region in FIG. 5B.

FIG. 6A illustrates another example embodiment of the electrodes inactive stylus tip 26. In this example, active stylus tip 26 contains oneor more electrodes, including electrodes 160, 162, and 164. Inparticular embodiments, including the one illustrated in FIG. 6A, one ormore of the electrodes in active stylus tip 26 extend along a portion ofthe length of active stylus tip 26 but do not extend the entire lengthof active stylus tip 26. In other embodiments, the electrodes in activestylus tip 26 each extend the length of active stylus tip 26. Theelectrodes in the embodiment illustrated in FIG. 6A each comprise avertical segment of active stylus tip 26. FIG. 6B illustrates analternate view of the example embodiment of active stylus tip 26illustrated in FIG. 6A. In FIG. 6B, active stylus tip 26 is viewedhead-on, such that each vertical segment of the tip in FIG. 6Acorresponds to a strip-like region in FIG. 6B. FIG. 6C illustrates yetanother embodiment, in which the electrodes (including electrodes 170,172, and 174) comprise vertical segments of active stylus tip 26 thatextend radially outward from the center shaft 41 in active stylus tip26. FIG. 6D illustrates an alternate view of the example embodiment ofactive stylus tip 26 illustrated in FIG. 6C. In FIG. 6D, active stylustip 26 is viewed head-on, such that each vertical segment of the tip inFIG. 6C corresponds to a radial segment in FIG. 6D.

FIG. 7A illustrates yet another example embodiment of the electrodes inactive stylus tip 26. In this example, active stylus tip 26 contains oneor more electrodes, including electrodes 260, 262, and 264. Theembodiment shown in FIG. 7A shows a grid of individual electrodes inactive stylus tip 26. The grid is formed from dividing active stylus tip26 into both horizontal and vertical segments. As such, each electrode,including electrodes 260, 262, and 264, comprises a vertically andhorizontally bounded area within active stylus 26. FIG. 7B illustratesan alternate view of the example embodiment of active stylus tip 26illustrated in FIG. 7A. In FIG. 7B, active stylus tip 26 is viewedhead-on, such that each horizontal segment of the tip in FIG. 7Acorresponds to a circular or ring-like region in FIG. 7B, and eachvertical segment of the tip in FIG. 7A corresponds to a strip-likeregion in FIG. 7B. FIG. 7C illustrates yet another embodiment in whichthe electrodes (including electrodes 270, 272, and 274) are arranged ina grid formation. The grid in FIG. 7C is formed from dividing activestylus tip 26 into both horizontal and vertical segments, with eachvertical segment extending radially outward from the center shaft 41 inactive stylus tip 26. FIG. 7D illustrates an alternate view of theexample embodiment of active stylus tip 26 illustrated in FIG. 7C. InFIG. 7D, active stylus tip 26 is viewed head-on, such that eachelectrode in the grid formation of FIG. 7C corresponds to a portion of aradial segment in FIG. 7D. In particular embodiments, one or moreelectrodes within the active stylus tip 26 may be surrounded by otherelectrodes within the active stylus tip 26.

FIGS. 8A and 8B illustrate yet another example embodiment of theelectrodes in active stylus tip 26. In this example, active stylus tipcontains one or more electrodes, including electrodes 360 and 362.Electrode 362 is surrounded by electrode 360. In the embodimentillustrated in FIGS. 8A and 8B, electrodes 362 and 360 comprise areasapproximating a cylinder and a concentric cylindrical ring within activestylus tip 26. If active stylus tip 26 is cut along imaginary plane 66,the cross section of active stylus tip 26 would appear as illustrated inFIG. 8B, approximating a circle and a concentric ring.

Although particular example embodiments of active stylus tip 26 havebeen described, the multiple electrodes of active stylus tip 26 may bearranged in any configuration or form any shape that is desirable forthe operation of active stylus 20. As an example, the electrodes in theactive stylus tip 26 may be arranged to create a unique identifyingsignature for the active stylus 20. In particular embodiments, theactive stylus tip 26 may have a nib region, and the electrodes in thisnib region may be arranged to achieve a desired result, such as thecapability to sense differences in pressure on the nib. As an example,the electrodes in the nib region may be arranged in a staggered patternto detect variations in pressure. Additionally, in particularembodiments, active stylus tip 26 may be an interchangeable tip.

The multiple electrodes of active stylus tip 26 may each be able toreceive signals from or send signals to other components of activestylus 20, a user, or device 52, without limitation. In particularembodiments, including those illustrated in FIGS. 5, 6, 7, and 8, theelectrodes of active stylus tip 26 may each receive and send signals viacenter shaft 41. As an example, the electrodes in active stylus tip 26may each receive signals from controller 50 via center shaft 41. Inparticular embodiments, a drive unit in controller 50 may supply signalsto each of the electrodes in active stylus tip 26 via center shaft 41.The multiple electrodes of active stylus tip 26 may also each sendsignals to controller 50 via center shaft 41. As an example, theelectrodes in active stylus tip 26 may each send signals to a sense unitin controller 50 via center shaft 41. In other embodiments, a processorin controller 50 may control the operation of the electrodes in activestylus tip 26, either via drive or sense units or directly. Inparticular embodiments, the multiple electrodes of active stylus tip 26may each be able to receive signals from or send signals to logic (e.g.multiplexer), mechanical switches, electrical or electronic circuits orcircuit elements (including, for example, operational amplifiers)

Each of the multiple electrodes in the active stylus tip 26 may be, byway of example and without limitation, a drive electrode, a senseelectrode, a guard electrode, or a ground electrode.

Active stylus 20 may receive signals from external sources, includingdevice 52, a user, or another active stylus. Active stylus 20 mayencounter noise when receiving signals. As examples, noise may beintroduced into the received signals from data quantization, limitationsof position-calculation algorithms, bandwidth limitations of measurementhardware, accuracy limitations of analog front ends of devices withwhich active stylus 20 communicates, the physical layout of the system,sensor noise, charger noise, device noise, stylus circuitry noise, orexternal noise. The noise external to active stylus 20 is oftenomnidirectional and may be modeled as white noise, and, in specificcases, Gaussian white noise.

Active stylus 20 may transmit signals based in part on the determinationthat it received a signal, and not simply noise, from a signal source.As an example, active stylus 20 may determine whether it received asignal from device 52 by comparing the received signal to a signalthreshold. If the received signal satisfies the threshold requirement(e.g., meets the minimum value of this signal threshold), active stylus20 may process the received signal, including, for example, amplifyingor phase-shifting the received signal, in order to create a transmitsignal to transmit back to device 52. It may be desirable for activestylus 20 to, for example, dynamically adjust the threshold fordetermining that a received signal contains a signal from device 52, orany other signal source, and not merely noise. As an example, if thesignal threshold is too low, active stylus 20 may incorrectly determinethat a pure noise signal is actually a signal from device 52, proceed toprocess the noise signal, and incorrectly transmit a response signal. Asanother example, if signal threshold is too high, active stylus 20 mayincorrectly determine that a signal from device 52 is purely a noisesignal and fail to process the received signal and transmit a responsesignal. The threshold adjustment may be based on some factors.

FIG. 9 illustrates an example embodiment of active stylus 20 in whichactive stylus 20 is capable of adjusting the threshold by which itdetermines if a signal, and not merely noise, was received. Inparticular embodiments, a signal S is received by one or more electrodescapable of sensing signals in active stylus 20. These electrodes mayreside on active stylus tip 26. The signal S received by the electrodesin active stylus 20 may then be transmitted from the electrodes tocontroller 50. In particular embodiments, signal S is transmitted tocontroller 50 via center shaft 41. Controller 50, as discussed above,may include, without limitation, a drive unit, a sense unit, a storageunit, and a processor unit. The components illustrated in FIG. 9 mayreside in controller 50, and in certain embodiments may be a part of theprocessor unit of controller 50.

In particular embodiments including the one illustrated by FIG. 9,received signal S may be amplified by amplifier 100. Amplifier 100 maybe any suitable amplifier, including a digital or an analog amplifier.After the signal S is amplified, it may be filtered by filter 200.Filter 200 may be an analog filter including analog circuit components,such as one or more resistors or capacitors. In other embodiments,filter 200 may be a digital filter, such as a finite-impulse-response(FIR) filter, or a Kalman filter. Filter 200 may be any suitable filterfor processing the received signal, including, for example, a filter fornoise removal.

Referring to FIG. 9, amplified and/or filtered signal S, denotedS_filter, proceeds to control processor 300. Control processor 300 maybe a microcontroller. Control processor 300 includes comparator 310 andprocessor 320. Comparator 310 may, in particular embodiments, be ananalog comparator, including analog circuitry. In other embodiments,comparator 310 may be a digital comparator, and in yet otherembodiments, comparator 310 may be a processor. Comparator 310 receivesas input S_filter. Comparator 310 then compares S_filter to at least onesignal threshold to determine whether S_filter represents noise alone ora received signal in addition to noise. As an example, if S_filter is avoltage, comparator 310 compares S_filter to a voltage threshold valueV_th to determine whether S_filter is less than, equal to, or greaterthan V_th. In this example, if S_filter is equal to or greater thanV_th, comparator 310 determines that S_filter contains a signal, and notmerely noise, and outputs this determination to processor 320 via outputline 330. In particular embodiments, if S_filter meets or exceeds thesignal threshold V_th, processor 320 may then output S_filter forfurther processing by active stylus 20. In addition to having a signalthreshold V_th, comparator 310 may also have a threshold for diagnosticpurposes. As an example, comparator 310 may have a second threshold,V_diag, with a value different from V_th, and the output of a comparisonof S_filter and V_diag is sent to processor 320 via output line 340. Inthis example, the determination by comparator 310 whether S_filter meetsor exceeds signal threshold V_th controls whether or not S_filter isprocessed further by active stylus 20, and the determination whetherS_filter meets or exceeds diagnostic threshold V_diag allows processor320 to determine future values of V_th or V_diag.

In the example embodiment of FIG. 9, comparator 310 may also outputadditional data to processor 320. Comparator 310 may analyze S_filterand output any type of information about S_filter to processor 320 viaoutput line 340. As an example, comparator 310 may calculate thesignal-to-noise ratio (SNR) of S_filter and send this information toprocessor 320. As another example, comparator 310 may determine theamplitude characteristics of S_filter and send this to processor 320. Asyet another example, comparator 310 may determine the frequencycharacteristics of S_filter, including the bandwidth of S_filter, andsend this to processor 320. Output line 340 may carry one or moresignals containing any type of relevant information about S_filter fromcomparator 310 to processor 320.

As illustrated in the example embodiment of FIG. 9, processor 320receives data from comparator 310 via output lines 330 and 340.Processor 320 may adjust threshold V_th or V_diag based on the datareceived from comparator 310. Additionally, processor 320 may adjustV_th or V_diag based on data received from any other components ofactive stylus 20, including other parts of controller 50 (such as thesense unit, drive unit, storage unit, or processor unit), memory 44,power source 48, or sensors 42. Processor 320 may send adjustedthreshold values of V_th and V_diag to comparator 310 via output line350. Additionally, processor 320 may send other types of data tocomparator 310 via output line 350 or additional output lines,including, for example, SNR cutoff values. Although FIG. 9 illustrates aparticular embodiment in which processor 320 receives data fromcomparator 310, processor 320 may also receive data from or send data toany part of active stylus 20. As an example, processor 320 may receivedata regarding known characteristics (such as bandwidth, phase,amplitude, or synchronization patterns) of the signal of interesttransmitted by a signal source such as device 52. As another example,processor 320 may receive data regarding the mode in which active stylus20 is operating (such as, for example, a hover mode).

In particular embodiments, processor 320 may adjust V_th so that V_th isapproximately proportional to the SNR of S_filter. As an example, if theSNR of S_filter is high, as may be the case when active stylus 20 isnear to a signal source like device 52, processor 320 may adjust V_thupward, so that the new value of V_th is higher than the old value ofV_th. This may allow for improved noise rejection by active stylus 20.As another example, if the SNR of S_filter is low or if the amplitude ofS_filter is low, as may be the case when active stylus 20 is far from asignal source like device 52, processor 320 may adjust V_th downward, sothat the new value of V_th is lower than the old value of V_th. This mayallow for improved signal detection by active stylus 20 in low SNR orlow amplitude situations.

In other embodiments, if processor 320 determines that comparator 310 isfalsely triggering too frequently on S_filter (that is, if comparator310 too frequently incorrectly determines that S_filter contains asignal when S_filter is purely noise), processor 320 may increase V_thto improve noise rejection. False triggering may occur more frequentlyin very low SNR situations where the amplitude or frequencycharacteristics of the noise are comparable to those of the signal.Thus, in particular embodiments, processor 320 may reduce V_th in lowSNR situations until some minimum value of V_th is reached (where falsetriggering occurs too frequently), at which point processor 320 mayincrease V_th to prevent further false triggering. In other embodiments,processor 320 may reduce V_th in low SNR situations until some minimumSNR value for S_filter is reached (such as, for example, an SNR of 1),at which point processor 320 may increase V_th to prevent further falsetriggering.

In yet other embodiments, if processor 320 determines that comparator310 is too frequently incorrectly rejecting S_filter as purely noise,processor 320 may decrease V_th to improve signal detection. Thus, inparticular embodiments, processor 320 may increase V_th until somemaximum value of V_th is reached (for example, where signal rejectionoccurs too frequently), at which point processor 320 may decrease V_thto prevent further signal rejection.

Processor 320 may use diagnostic threshold V_diag to determine if activestylus is operating in a low SNR range. For example, if V_th is set to 2volts, V_diag is set to 1.5 volts, and S_filter is consistently in therange between 1.5 and 2 volts (without meeting or exceeding 2 volts),comparator 310 will reject S_filter as a noise signal. Processor 32,however, may have data indicating that S_filter is not pure noise(based, for example, on known characteristics of the signal transmittedby device 52). Processor 320 may analyze the fact that S_filter meetsthe diagnostic threshold, V_diag, and not the signal detectionthreshold, V_th, and determine that active stylus 20 is operating in alow SNR range.

In addition to analyzing current data from comparator 310 and other datasources from active stylus 20, processor 320 may access storedinformation. As an example, processor 320 may access prior data valuesreceived from comparator 310 (such as threshold comparison outputs, SNRof S_filter, or amplitude of S_filter) or other components of activestylus 20 to determine future values of V_th or V_diag. Prior datavalues accessed by processor 320 may, for example, be stored inprocessor 320 or in memory 44. Initial or prior values for V_th orV_diag may also be accessed or stored by processor 320.

FIG. 10 illustrates an example method for dynamically adjusting a signaldetection threshold in active stylus 20. The method may start at step600, where a first signal is received. With reference again to FIG. 9,in particular embodiments, this step may occur when control processor300 receives S_filter from filter 200. At step 610, one or morecharacteristics of the first signal are determined. In particularembodiments, this step may occur in control processor 300, with certaincharacteristics determined by comparator 310 (including, for example,whether a threshold is met) and certain characteristics determined byprocessor 320 (including, for example, SNR). In particular embodiments,one of the characteristics determined for the first signal is whetherthe first signal satisfies the threshold requirement based on thecurrent value of the threshold. This may be determined by comparing thefirst signal to the current value of the threshold. At step 620, athreshold is adjusted based on the one or more characteristics of thefirst signal. This may result in the threshold having a new value. Inparticular embodiments, the steps illustrated in FIG. 10 may be repeatedany number of times (e.g., any number of iterations). For example,during a second iteration, a second signal may be received (returningback to step 600). One or more characteristics may be determined for thesecond signal at step 610. Again, one of the characteristics determinedfor the second signal is whether the second signal satisfies thethreshold requirement based on the current value of the threshold. Notethat the current value of the threshold may have been adjusted duringthe previous iteration. At step 620, the threshold may be adjusted againbased on the characteristics of the second signal.

In particular embodiments, processor 320 adjusts signal detectionthreshold V_th based on data received from comparator 310 and sendsadjusted V_th to comparator 310 via output line 350. In this manner,comparator 310, output lines 330 and 340, processor 320, and output line350 form a feedback loop for controlling the one or more signalthresholds against which S_filter is compared. Particular embodimentsmay repeat the steps of the method of FIG. 10, where appropriate.Moreover, although this disclosure describes and illustrates particularsteps of the method of FIG. 10 as occurring in a particular order, thisdisclosure contemplates any suitable steps of the method of FIG. 10occurring in any suitable order. Furthermore, although this disclosuredescribes and illustrates particular components, devices, or systemscarrying out particular steps of the method of FIG. 10, this disclosurecontemplates any suitable combination of any suitable components,devices, or systems carrying out any suitable steps of the method ofFIG. 10.

In particular embodiments of active stylus 20, the electrodes withinactive stylus 20 (such as, for example, those electrodes in activestylus tip 26) may be dynamically configured. As an example, theconfiguration of specific electrodes as drive (or transmit) or sense (orreceive) electrodes, or any other suitable type of electrode, may changedepending on the operation of active stylus 20. The operation of activestylus 20, without limitation, may include past, present, or futurecharacteristics relevant to the operation of active stylus 20. Asexamples, the operation of active stylus 20 may include characteristicsof active stylus 20, such as the mode (including, for example, hovermode) in which active stylus 20 is, was, or will be operating, or mayinclude characteristics of the environment in which active stylus 20 is,was, or will be operating, such as the noise level. By way of example,if active stylus 20 is operating close to device 52, more electrodes inactive stylus tip 26 may be configured as drive electrodes for improvedtransmission of signals from active stylus 20 to device 52. As anotherexample, if active stylus 20 is operating far from device 52, moreelectrodes in active stylus tip 26 may be configured as sense electrodesfor the sensing of signals from device 52. This may allow for improvedSNR of signals received by active stylus 20.

The dynamic configuration of electrode function in active stylus 20 may,in particular embodiments, occur in controller 50. As examples,processor unit, drive unit, sense unit, storage unit, or any combinationthereof may dynamically configure the function of the electrodes inactive stylus 20. Although this disclosure describes and illustratescontroller 50 as carrying out the dynamic configuration of electrodefunction in active stylus 20, any suitable component of active stylus 20may perform this configuration. In particular embodiments, thereassignment or configuration of electrodes in active stylus 20 mayoccur via logic. As an example, a multiplexer in controller 50 mayreceive input from a processor unit in controller 50 directing themultiplexer as to which electrodes should be drive or sense electrodes.The output of the multiplexer would be sent, either directly orindirectly, to the electrodes in active stylus 20, thereby configuringthese electrodes according to controller 50. In some embodiments, thismultiplexer may be connected to the drive unit, the sense unit, or bothunits in the controller 50, rather than directly to electrodes in activestylus tip 26. In other embodiments, the reassignment or configurationof electrodes in active stylus 20 may occur mechanically. For example,when the active stylus 20 is pressed against a device 52, the pressuremoves certain electrodes in active stylus tip 26 such that they changefrom contacting a sense line (leading to controller 50) to contacting adrive line (coming from controller 50). In yet other embodiments, thereassignment or configuration of electrodes in active stylus 20 mayoccur electrically or electronically using, for example, circuits withoperational amplifiers.

Controller 50 may receive inputs from one or more components of activestylus 20 that it uses to determine electrode configuration. In oneembodiment, controller 50 may receive input from sensors 42. As anexample, controller 50 may receive input from an accelerometer (one ofsensors 42); one such input from an accelerometer may be that the stylusis in a titled configuration with respect a device 52. In this example,if stylus is tilted, those electrodes in active stylus tip 26 tiltedcloser to device 52 will have a stronger coupling with device 52 thanthose electrodes in active stylus tip 26 on a far side of active stylus20. Thus, controller 50 may, based on this input from sensors 42,reconfigure more of those electrodes in active stylus tip 26 closer todevice 52 to be transmit electrodes and reconfigure more of thoseelectrodes in active stylus tip 26 farther from device 52 to be receiveelectrodes. This may serve to improve the receive signal SNR at activestylus 20. In other embodiments, controller 50 may receive input from agyroscope, a vibration detector, an optical sensor, a capacitive sensor,or any other type of sensor in sensors 42.

With reference to FIG. 5A as an example, in particular embodiments,adjacent electrodes may be configured to have different functions. As anexample, electrodes 60 and 64 may be configured by controller 50 to bedrive (or transmit) electrodes, and electrode 62 may be configured as aground electrode. As another example, electrode 60 may be configured bycontroller 50 to be a drive electrode, electrode 64 may be configured asa sense (or receive) electrode, and electrode 62 may be configured as ashield electrode to prevent unwanted coupling between sense electrode 60and transmit electrode 64. Controller 50 may choose to configureelectrode 62 as a shield electrode if, for example, it receives inputsignals from electrode 60 showing a characteristic ringing due to thetransmission from electrode 64.

In other embodiments, controller 50 may configure electrodes in activestylus 20 based on the mode in which active stylus 20 is operating. Forexample, if active stylus 20 is operating in hover mode, controller 50may obtain this information from sensor 42, memory 44, (or any othercomponent of active stylus 20) and configure more electrodes in activestylus tip 26 to function as receive electrodes in order to boost theSNR of the signal received by active stylus 20. As another example, ifactive stylus 20 is operating in a mode where it is directly in contactwith device 52, controller 50 may configure more electrodes in stylustip 26 to operate as transmit electrodes because the SNR of the receivedsignal is likely to be high. Controller 50 may choose to configure acertain percentage of the electrodes of active stylus 20 to be ground,guard, shield, drive, or sense electrodes, as well as any other suitableelectrode function.

In yet other embodiments, controller 50 may configure electrodes inactive stylus 20 based on the inputs from the electrodes themselves, aswell as based on any processed version of these inputs. As an example,if controller 50 determines that the SNR of the signal or signalsreceived by the electrodes in active stylus tip 26 is too low (lowerthan a preset or dynamic threshold, for example), controller 50 mayconfigure more electrodes of active stylus 20 to be receive electrodes.Similarly, if controller 50 determines that the amplitudes of signalsreceived by electrodes in active stylus tip 26 are too low, it mayreconfigure the electrodes in active stylus 20. As a final example, ifcomparator 310 (discussed above with respect to FIG. 9) is falselytriggering too often, controller 50 may reconfigure more electrodes inactive stylus 20 to be receive electrodes. The configuration ofelectrodes in active stylus 20 may be done in conjunction with anysuitable algorithm for active stylus 20, including, for example, dynamicadjustment of receive signal thresholds, as discussed above with respectof FIGS. 9 and 10. Additionally, the configuration of electrodes inactive stylus 20 may be done on an ongoing, dynamic basis, such that thecurrent configuration of electrodes provides input to controller 50,which then decides a new configuration of electrodes in active stylus 20based on the input.

FIG. 11 illustrates an example method for dynamically configuringelectrodes in active stylus 20. The method may start at step 1100, whereone or more characteristics of active stylus 20 are determined. Examplesof such characteristics may include, without limitation, output fromelectrodes in active stylus tip 26, the mode of operation of activestylus 20, or output from accelerometer or other sensors 42. At step1110, one or more electrodes in active stylus 20 are configured based onthese characteristics. As discussed above, steps 1100 and 1110 may, inparticular embodiments, occur in controller 50 and in the communicationof signals between controller 50 and electrodes in active stylus tip 26.Additionally, the configuration of an electrode need not result in achange of that electrode's function. That is, if an electrode ispresently configured to be a drive electrode, controller 50 mayconfigure the electrode such that it remains a drive electrode. Inparticular embodiments, the steps illustrated in FIG. 11 may be repeatedany number of times (e.g., any number of iterations). For example,during a second iteration, a second set of characteristics of activestylus 20 may be accessed (returning back to step 1100). This second setof characteristics may include the previous configuration of one or moreelectrodes in active stylus 20. In step 1110 of this second iteration,one or more electrodes in active stylus 20 are configured based on thesesecond characteristics. The new configuration of the one or moreelectrodes may be the same or different than the previous configuration.Although this disclosure describes and illustrates particular steps ofthe method of FIG. 11 as occurring in a particular order, thisdisclosure contemplates any suitable steps of the method of FIG. 11occurring in any suitable order. Furthermore, although this disclosuredescribes and illustrates particular components, devices, or systemscarrying out particular steps of the method of FIG. 11, this disclosurecontemplates any suitable combination of any suitable components,devices, or systems carrying out any suitable steps of the method ofFIG. 11.

Herein, reference to a computer-readable non-transitory storage mediumencompasses a semiconductor-based or other integrated circuit (IC)(such, as for example, a field-programmable gate array (FPGA) or anapplication-specific IC (ASIC)), a hard disk, an HDD, a hybrid harddrive (HHD), an optical disc, an optical disc drive (ODD), amagneto-optical disc, a magneto-optical drive, a floppy disk, a floppydisk drive (FDD), magnetic tape, a holographic storage medium, asolid-state drive (SSD), a RAM-drive, a SECURE DIGITAL card, a SECUREDIGITAL drive, or another suitable computer-readable non-transitorystorage medium or a combination of two or more of these, whereappropriate. A computer-readable non-transitory storage medium may bevolatile, non-volatile, or a combination of volatile and non-volatile,where appropriate.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

This disclosure encompasses all changes, substitutions, variations,alterations, and modifications to the example embodiments herein that aperson having ordinary skill in the art would comprehend. Moreover,reference in the appended claims to an apparatus or system or acomponent of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

What is claimed is:
 1. A method comprising: identifying a change in asignal-to-noise ratio of one or more signals received wirelessly by astylus, the stylus being operable to communicate wirelessly with adevice through a touch sensor of the device, the stylus comprising oneor more electrodes, a first electrode of the one or more electrodesconfigured to operate as a first electrode type of a plurality ofelectrode types, each electrode type defining a function of theelectrode, wherein the plurality of electrode types comprise: a driveelectrode type; and a sense electrode type; determining, based on thechange in the signal-to-noise ratio, a second electrode type of theplurality of electrode types for the first electrode; and dynamicallyconfiguring, based on the change in the signal-to-noise ratio, the firstelectrode to operate as the second electrode type.
 2. The method ofclaim 1, wherein the stylus further comprises one or morecomputer-readable non-transitory storage media embodying logic that isoperable when executed to dynamically configure one or more of theelectrodes.
 3. The method of claim 1, wherein the stylus furthercomprises mechanical means operable to dynamically configure one or moreof the electrodes.
 4. The method of claim 1, wherein the stylus furthercomprises electrical or electronic means operable to dynamicallyconfigure one or more of the electrodes.
 5. The method of claim 1,wherein dynamically configuring an electrode comprises configuring theelectrode to transmit signals.
 6. The method of claim 1, whereindynamically configuring an electrode comprises configuring the electrodeto receive signals.
 7. The method of claim 1, wherein: the styluscomprises a tip; and the one or more electrodes are located in the tip.8. The method of claim 1, wherein dynamically configuring, based on thechange in the signal-to-noise ratio, the first electrode comprisesdynamically configuring the first electrode based on the change in thesignal-to-noise ratio and on an operating mode of the stylus.
 9. Themethod of claim 1, wherein dynamically configuring, based on the changein the signal-to-noise ratio, the first electrode comprises dynamicallyconfiguring the first electrode based on the change in thesignal-to-noise ratio and on one or more signals received from: at leastone of the one or more electrodes; or a sensor on the stylus.
 10. Themethod of claim 1, wherein the plurality of electrode types furthercomprise one or more of: a ground electrode type, a shield electrodetype, and a guard electrode type.
 11. A system comprising: a devicecomprising a touch sensor; and a stylus, the stylus comprising one ormore electrodes; the stylus being operable to: communicate wirelesslywith the device through the touch sensor of the device; identify achange in a signal-to-noise ratio of one or more signals receivedwirelessly by the stylus, a first electrode of the one or moreelectrodes configured to operate as a first electrode type of aplurality of electrode types, each electrode type defining a function ofthe electrode, wherein the plurality of electrode types comprise: adrive electrode type; and a sense electrode type; determine, based onthe change in the signal-to-noise ratio, a second electrode type of theplurality of electrode types for the first electrode; and dynamicallyconfigure, based on the change in the signal-to-noise ratio, the firstelectrode to operate as the second electrode type.
 12. The system ofclaim 11, wherein the stylus further comprises one or morecomputer-readable non-transitory storage media embodying logic that isoperable when executed to dynamically configure one or more of theelectrodes.
 13. The system of claim 11, wherein the stylus furthercomprises mechanical means operable to dynamically configure one or moreof the electrodes.
 14. The system of claim 11, wherein the stylusfurther comprises electrical or electronic means operable to dynamicallyconfigure one or more of the electrodes.
 15. The system of claim 11,wherein dynamically configuring an electrode comprises configuring theelectrode to transmit signals.
 16. The system of claim 11, whereindynamically configuring an electrode comprises configuring the electrodeto receive signals.
 17. The system of claim 11, wherein: the styluscomprises a tip; and the one or more electrodes are located in the tip.18. The system of claim 11, wherein the stylus is further operable todynamically configure the first electrode based on an operating mode ofthe stylus.
 19. The system of claim 11, wherein the stylus is furtheroperable to dynamically configure the first electrode based on one ormore signals received from: at least one of the one or more electrodes;or a sensor on the stylus.
 20. The system of claim 11, wherein theplurality of electrode types further comprise one or more of: a groundelectrode type, a shield electrode type, and a guard electrode type.